The present application is a continuation proposal for an ongoing longitudinal study of the effects of exposure to conflict and violence on the mental health and behavior of Palestinian and Israeli youth. Three cohorts of youth (originally ages 8, 11, and 14) have been assessed three times at one-year intervals. Analyses of the data collected through June 2010 have shown that exposure to ethnic-political and war violence is related to subsequent post-traumatic stress symptoms and aggression directed at peers. The goals of the current proposal are to continue analyses with the three waves of data collected by June 2010 and to collect one more wave of data with a more intense focus on the older cohort as they now reach adulthood (age 20 in 2013) in order to examine effects of cumulative exposure to violence on clinical syndromes, substance use, antisocial and aggressive behavior, and endorsement of politically-motivated violence. Additionally, we will examine age-relevant potential protective factors that we did not previously assess for this older cohort (e.g., civic engagement, employment, constructive activities, political activism, and post traumatic growth). Our focus on the older cohort is motivated by the recognition that early adulthood is a period in which new opportunities and experiences present challenges to adjustment and when age-salient protective factors may moderate the impact of persistent exposure to violence. However, for all age cohorts, we propose to extend our assessment of mental health outcomes and extend our examination of the role of emotional reactivity in response to ethnic-political violence exposure by collecting bio-markers (e.g., cortisol) and assessing skin conductance in response to viewing a video depicting interpersonal violence. This will allow us to test key theoretical propositions concerning mediating cognitive and emotional processes that might account for the long-term effects of violence exposure and distinguish between those highly exposed youth who display more externalizing problems and those who display more internalizing problems. PUBLIC HEALTH RELEVANCE: The present application is a continuation proposal for an ongoing longitudinal study of the effects of exposure to ethnic-political conflict and violence on the mental health and behavior of Palestinian and Israeli youth (three cohorts starting at ages 8, 11, and 14) who have been assessed three times at one-year intervals. We will re-interview youth in all three cohorts, but with a particular focus on the oldest cohort (age 20 in 2013), to examine the effects of cumulative exposure to ethnic-political violence on clinical syndromes, substance use, antisocial and aggressive behavior, and risk for participation in political violence for these youth who are on the verge of adulthood and to examine factors (e.g., civic engagement, employment, constructive activities, political activism, post traumatic growth) that might protect them against these outcomes; and for all age cohorts, to test social-cognitive and emotional factors (e.g., deregulated stress response systems) that might account for the long-term effects of exposure on mental health and aggression. The results of this new phase will add significant value to our existing data by presenting clinical diagnostic information linked to therapeutically- meaningful bio-behavioral and social-cognitive mechanisms impacted by long-term exposure to violence, thus adding new and valuable insights to the design of targeted interventions for children coping with the negative effects of violence exposure.